Mass Transport during the Codeposition of Metals

If mixed complexes containing metals to be codeposited are not formed in the solution, regularities of mass transport remain the same as considered in Chapter 3  

1) It is assumed for simplicity that the charge numbers of both metal ions are the same. 

Electrolytic deposition of tin and cobalt alloys has found extensive applications in modern electroplating. Some outstanding properties of tin such as nontoxicity. 

Attention in the investigations cited was focused on problems of an applied nature, underlining the influence of the solution composition and electrolysis conditions on the phase and elemental composition of coatings. Atheoretical analysis of kinetics and the mechanism of electrode processes were often omitted. In this connection, we present next the main results of our investigations concerning the kinetics of codeposition of tin and cobalt in the solutions containing citric acid (LHJ [15,16]. 

When modeling codeposition of Sn and Co, the distribution of complexes and protonated species of ligand should be primarily estimated. Such data may be obtained through the solution of material balance equation as described in Chapter 1. In the case of acid solutions (pH 7), the following basic equilibria should be taken into account first  

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